/*
 * Copyright (c) 2007-2012, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 1999-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: BasicTestIterator.java,v 1.2.4.1 2005/09/14 19:45:20 jeffsuttor Exp $
 */
package com.sun.org.apache.xpath.internal.axes;

import com.sun.org.apache.xml.internal.dtm.DTM;
import com.sun.org.apache.xml.internal.dtm.DTMFilter;
import com.sun.org.apache.xml.internal.dtm.DTMIterator;
import com.sun.org.apache.xml.internal.utils.PrefixResolver;
import com.sun.org.apache.xpath.internal.compiler.Compiler;
import com.sun.org.apache.xpath.internal.compiler.OpMap;

/**
 * Base for iterators that handle predicates.  Does the basic next
 * node logic, so all the derived iterator has to do is get the
 * next node.
 */
public abstract class BasicTestIterator extends LocPathIterator {
    static final long serialVersionUID = 3505378079378096623L;

    /**
     * Create a LocPathIterator object.
     *
     * @param nscontext The namespace context for this iterator,
     * should be OK if null.
     */
    protected BasicTestIterator() {
    }

    /**
     * Create a LocPathIterator object.
     *
     * @param nscontext The namespace context for this iterator,
     * should be OK if null.
     */
    protected BasicTestIterator(PrefixResolver nscontext) {

        super(nscontext);
    }

    /**
     * Create a LocPathIterator object, including creation
     * of step walkers from the opcode list, and call back
     * into the Compiler to create predicate expressions.
     *
     * @param compiler The Compiler which is creating
     * this expression.
     * @param opPos The position of this iterator in the
     * opcode list from the compiler.
     *
     * @throws javax.xml.transform.TransformerException
     */
    protected BasicTestIterator(Compiler compiler, int opPos, int analysis) throws javax.xml.transform.TransformerException {
        super(compiler, opPos, analysis, false);

        int firstStepPos = OpMap.getFirstChildPos(opPos);
        int whatToShow = compiler.getWhatToShow(firstStepPos);

        if ((0 == (whatToShow & (DTMFilter.SHOW_ATTRIBUTE | DTMFilter.SHOW_NAMESPACE | DTMFilter.SHOW_ELEMENT | DTMFilter.SHOW_PROCESSING_INSTRUCTION))) || (whatToShow == DTMFilter.SHOW_ALL))
            initNodeTest(whatToShow);
        else {
            initNodeTest(whatToShow, compiler.getStepNS(firstStepPos), compiler.getStepLocalName(firstStepPos));
        }
        initPredicateInfo(compiler, firstStepPos);
    }

    /**
     * Create a LocPathIterator object, including creation
     * of step walkers from the opcode list, and call back
     * into the Compiler to create predicate expressions.
     *
     * @param compiler The Compiler which is creating
     * this expression.
     * @param opPos The position of this iterator in the
     * opcode list from the compiler.
     * @param shouldLoadWalkers True if walkers should be
     * loaded, or false if this is a derived iterator and
     * it doesn't wish to load child walkers.
     *
     * @throws javax.xml.transform.TransformerException
     */
    protected BasicTestIterator(Compiler compiler, int opPos, int analysis, boolean shouldLoadWalkers) throws javax.xml.transform.TransformerException {
        super(compiler, opPos, analysis, shouldLoadWalkers);
    }

    /**
     * Get the next node via getNextXXX.  Bottlenecked for derived class override.
     * @return The next node on the axis, or DTM.NULL.
     */
    protected abstract int getNextNode();

    /**
     *  Returns the next node in the set and advances the position of the
     * iterator in the set. After a NodeIterator is created, the first call
     * to nextNode() returns the first node in the set.
     *
     * @return  The next <code>Node</code> in the set being iterated over, or
     *   <code>null</code> if there are no more members in that set.
     */
    public int nextNode() {
        if (m_foundLast) {
            m_lastFetched = DTM.NULL;
            return DTM.NULL;
        }

        if (DTM.NULL == m_lastFetched) {
            resetProximityPositions();
        }

        int next;

        com.sun.org.apache.xpath.internal.VariableStack vars;
        int savedStart;
        if (-1 != m_stackFrame) {
            vars = m_execContext.getVarStack();

            // These three statements need to be combined into one operation.
            savedStart = vars.getStackFrame();

            vars.setStackFrame(m_stackFrame);
        } else {
            // Yuck.  Just to shut up the compiler!
            vars = null;
            savedStart = 0;
        }

        try {
            do {
                next = getNextNode();

                if (DTM.NULL != next) {
                    if (DTMIterator.FILTER_ACCEPT == acceptNode(next))
                        break;
                    else
                        continue;
                } else
                    break;
            } while (next != DTM.NULL);

            if (DTM.NULL != next) {
                m_pos++;
                return next;
            } else {
                m_foundLast = true;

                return DTM.NULL;
            }
        } finally {
            if (-1 != m_stackFrame) {
                // These two statements need to be combined into one operation.
                vars.setStackFrame(savedStart);
            }
        }
    }

    /**
     *  Get a cloned Iterator that is reset to the beginning
     *  of the query.
     *
     *  @return A cloned NodeIterator set of the start of the query.
     *
     *  @throws CloneNotSupportedException
     */
    public DTMIterator cloneWithReset() throws CloneNotSupportedException {

        ChildTestIterator clone = (ChildTestIterator) super.cloneWithReset();

        clone.resetProximityPositions();

        return clone;
    }

}
